1. Field of Invention
The present invention relates to a human eye adaptive optical visual perception training method and a training apparatus capable of several functions including eye aberration correction, visual function measurement (including but not limited to a contrast threshold measurement), visual perception training. Finer visual stimulus is obtained by correcting human eye aberration by means of an adaptive optical system, and then the human eye acuity limit can be measured, and the visual perception training effect and visual function of the human eye can be efficiently improved by performing visual perception training with such apparatus.
2. Description of Prior Art
The development of vision of human is a progressive process. The eyeballs have grown to a certain extent when a person is born. However, the growing is not full in terms of anatomy or physiological function, and the eyeballs will continue growing in a long term thereafter. The normal development of Vision requires two conditions, one is the postnatal developing processing, and the other is external visual stimulus. Ages 0-7 are the golden stage for vision development, during which if the eyes are shaded for a long time, the vision will not develop and remain at a low level due to deficiency of normal visual stimulus from external images.
The function of the eyeballs is dominant for the vision of a person. Usually, an eyeball has no so perfect optical characteristic and whose capability is affected by various factors including, for example, diffraction of pupil, aberration from cornea and lens and dispersion of aqueous humor (R. Williams, D., & Hofer, H., Formation and Acquisition of the Retinal Image. In: J.S.W. Leo M. Chalupa (Ed.) The Visual Neurosciences, the MIT Press, Cambridge, Mass., London, England, 2003).
Generally, the effect due to the dispersion of aqueous humor is so small that is negligible. The aberration is large while the diffraction is small if the pupil becomes large, whereas the aberration is small while the diffraction is large if the pupil becomes small. The aberration of human eyes includes low-order aberration and high-order aberration, the former can be easily corrected but the latter is difficult to be corrected.
Recently, many researchers (Geun-Young Yoon and David R. Williams, Visual Performance after correcting the monochromatic and chromatic aberrations of the eye, J. Opt. Soc. Am. A/Vol. 19, No. 2) attempt to apply the Adaptive Optics technology in the research of vision to explore the relationship between the high-order aberration and normal vision and to explore the limit for spatial vision. However, it is not agreed whether a supernormal vision can be reached after all the aberration (including the low order and the high order) of a visual system are corrected (Marcos, S., Sawides, L., Gambra, E., & Dorronsoro, C., Influence of adaptive-optics ocular aberration correction on visual acuity at different luminances and contrast polarities. 8: 1-12, 2008).
A visual system can only correctly develop with the aid of visual experiences (Chiu, C., & Weliky, M., The Role of Neural Activity in the Development of Orientation Selectivity. In: J.S.W. Leo M. Chalupa (Ed.) The Visual Neurosciences, The Mit Press, Cambridge, Mass., London, England, 2003). The development of a fine acuity needs the fine development of the visual nervous system which depends on clarity degree of imaging on the retina for the optical system of an eyeball. An image cannot be clearly generated on the retina due to the high-order aberration and dispersion. The spatial cut off frequency that can be differentiated by the visual nervous system will be no larger than the highest spatial frequency of the image generated on the retina by the eyeballs.
The visual perception leaning process shows that the identification capability of the nervous system for a certain image will be largely improved via learning, which indicates that the nervous system is trainable even for an adult. Many psychological tests reveal that an adult can increase his success ratio and speed for a lot of visual perception tasks by learning (Zhou Y F, Huang C B, Xu P J, Tao L M, Qiu Z P, Li X R and Lu Z L, Perceptual Learning Improves Contrast Sensitivity and Visual Acuity in Adults with Anisometropic Amblyopia. Vision Research, 46(5): 739-750, 2006). However, the prior visual perception learning process uses eyeglass to correct the low-order aberration, and an image cannot be clearly generated on the retina due to the still existed high-order aberration and dispersion. Accordingly, the simple visual perception leaning process improves the visual function to an extent limited by the clarity of the image.
In view that the visual nervous system is trainable, the present invention combines the adaptive optical aberration correction technique and the visual perception learning technique. The quality of the image generated on the retina can be largely improved after the aberration is corrected through the adaptive optical technique. If the visual perception leaning process is conducted with such fine visual stimulus, the acuity of the visual nervous system can be enhanced, and thereby the visual perception training effect and visual function of human eyes can be efficiently improved.